N62 minimum valve lift

[garrett.fell]

Hello all. It's been a while since I've posted anything here - but I read this forum on a near daily basis.

So last night I decided to fiddle around with INPA/DIS and set the minimum valve opening from the stock .3mm to the "other" available setting of .8mm. Although I haven't had rough running problems on start in quite some time they've popped back up since it's become cold outside (Chicago). Even better it's not predictable. Sometimes it happens and other times it does not given basically the same low temperatures. I get random cylinder misfires on pretty much every single cylinder. It's not isolated to just a few.

Upon making this adjustment the engine stumbled a little bit and immediately seemed to run MUCH smoother. I am impressed!

Now during he procedure the software makes
Some references to the "downside" of doing this with worse gas mileage and performance "issues". It also suggests that it's not an approved function for the E53 but let's you do it anyway.

I guess I can understand the worsening gas mileage (probably attributed to idle fuel consumption) but don't really get the "performance" aspect of this unless you get less lift overall after making this adjustment. Also don't understand why it wouldn't be approved for the E53. The engine is an N62 but I believe it's been tweaked a bit for the E53 as the overall HP and torque specs and slightly different from the other applications.

I guess my question is - does anyone have any practical experience with making this adjustment and seen negative effects and put it back to the stock setting of .3mm? Thanks!




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[SlickGT1]

I have no idea, but you have balls. And I am subscribing.

[garrett.fell]

Yeah maybe a bit ballsey. I'll tell you. The difference in smoothness is very noticeable! I haven't heard it run this nicely in the nearly 5 years I've owned it!

This was just idling in the garage. I have not had a chance to take it on a run yet.


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[SlickGT1]

I would like to see what happens when you punch it.

[garrett.fell]

Curious - What are you anticipating? I did notice that from an idle when stabbing the gas a bit it seemed to "delay" a bit....it may have done that before though.

I also noticed on a relatively warm start it seemed to hold the idle-up a little higher for a second or two before coming back down to 600-ish. I think this was new behavior but I am not sure.


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[SlickGT1]

wait, which valve opening are you talking about. Idle valve.

Yea nothing will happen i think. But still curious how this works while driving.

[garrett.fell]

I am talking about the BMW valvetronic system. It's variable valve lift as opposed to variable valve timing. They vary the valve lift to influence engine airflow and engine RPM as opposed to doing that with a butterfly valve in the throttle body.

Crazy stuff.

The "setting" I did changes the minimum lift to .8mm vs .3mm.

I think the theory is after things wear a bit and cold temps will mess up the cylinder "filling potential" as the valves might not be lifting enough initially to ensure good airflow and smooth running at idle.


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[4.8isX5]

I have messed with this since about a year and a half ago. I actually found it when i was researching everything on the motor to band aid the idle smoke issue.


When i had the valve lift raised it would smoke less and take longer for it to happen.

It also changes your powerband, the more lift the engine wont feel as revvy or powerful in midrange however when you fully stomp on it , the ass dyno says it pulls better then stock setting.

Some people have used it to fix the issue you described with idle and misfires on 545s 745s etc, not many people know about this setting. And being able to alter the lift on valvetronic...

When i get my car on a dyno sometime this year im going to change certain things like this for example to see if there is a difference.

Stock is not .3 it is the .099 setting. You may have other worn parts say intermediate levers and it hs adjusted for that which is why thats what it is. I have hooked up and checked on a few diff 4.8s.

Another interesting thing when you are editing the settings the car stumbles for a second when you made over about .25 of a change in lift, if you dont have a loud exhaust like mine you wont notice, it does change idle sound and exhaust note of the motor slightly.

[LVP]

I have messed with this setting to deal with my intermediate levers that cause the misfires on starts in cold weather. I can't remember what mine is at now, but I think it's stock setting. It's misfiring nicely as the temps drop below freezing, so I'll connect this weekend and have a go. I think the engine needs to be cold to make the adjustment though. I recall attempting it when the engine was too warm.

[garrett.fell]

The intermediate lever "test" is done on a cold engine. The minimum valve lift adjustment is done on an engine more or less "at temperature".


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